In certain applications of PTC polymer materials, a sheet of PTC polymer with faces on opposite sides is sandwiched between two electrodes in the form of sheets of electrically conductive material, and electric terminals are mechanically and electrically connected to the electrodes and to mounting elements in an electric circuit. The terminals or terminations are attached to the electrodes with solder or welded. They are likely to be themselves rigid and to be rigidly attached to the mounting elements. For example, in a door lock motor, such a PTC device is snapped into the end cap of a motor on one end and riveted in place at its opposite end.
Stresses placed on the PTC element and it electrodes as a result of attachment in its application and particularly in the elongation of the terminations with temperature when the element is rigidly connected and is cycled in use, can, by placing the polymeric element in shear or tension, cause a permanent change in PTC characteristics.
At the same time, it is desirable that the terminations be dimensionally fixed at the time that they are attached to the mounting element.
One of the objects of this invention is to provide a simple, economically acceptable, and dependable polymeric PTC element construction that will obviate or minimize changes in PTC characteristics as a result of the mounting of the element.
Other objects of this invention will be apparent to those skilled in the art in light of the following description and accompanying drawings.